1. Field of the Invention
The present invention relates to a control device of a data transmission system configured so as to connect said control device to a management device via network, wherein said control device numerically controls operation of a machining motion mechanism of an NC machine tool and is arranged to make it capable of data communication, and to the transmission system.
2. Description of the Prior Art
An NC machine tool comprises a machining motion mechanism, such as a main spindle unit and a feed mechanism or the like which are a motion mechanism for machining a work piece, and a control device which controls operation of this machining motion mechanism, and this control is performed based on various kinds of data for use in control, such as those for machining program, amounts of pitch error compensation, and amounts of tool offset.
Said data for use in control is stored in a suitable storage section of the control device, and can be updated and outputted via an input/output device arranged in the operating panel or the like as needed.
In addition, said data for use in control is roughly classified into two categories: one needs to be updated in order for an operator of the NC machine tool to perform suitable machining operation as the need arises as represented by the amounts of tool offset; and the other is related to fundamental performance of the NC machine tool, such as a time constant used for control of a main spindle motor and a feed motor. Then, with regard to the former, in general, the operator can update it freely, and with regard to the latter, it is set so that the operator cannot update it but only a maintainer well versed in the NC machine tool can perform the necessary update.
By the way, in recent years, by connecting each control device of a plurality of NC machine tools to a data management device via network such as LAN, a central management of the data stored in each control device through the data management device has been performed as a way for transferring the data stored in each control device to the data management device for storing the same therein, and on the contrary, for suitably sending the data from the data management device to each control device for use in updating the data stored in each control device.
Then, formerly, a data update by said data management device has become available for all data stored in each control device, for this reason, on data, such as said amounts of tool offset, which need to be updated in order for the operator to perform suitable machining as the need arises, the update has also been made available by said data management device.
However, in a situation where the update can be freely performed by the data management device side on said amounts of tool offset or the like, since it may happen that data, such as the amounts of tool offset, is accidentally updated by the data management device when the operator does not become aware, there has been a fear that machining accuracy would decrease, or a serious accident caused by interference between a tool and a work piece might happen.
The present invention is made in view of the above actual situation, the object thereof is to provide the control device which is arranged to become capable of data communication and can increase the security of the data stored therein, and the transmission system provided therewith.